The prevalence of obesity among children aged 2-5 years remains significantly high and disproportionately across race and ethnicity. Compared to the prevalence of obesity in non-Hispanic White preschoolers (3.5%), rates in Hispanic children were almost 5 times as high (16.7%). One modifiable risk factor significantly related to obesity risk is the duration of sleep. There is considerable longitudinal evidence linking shorter sleep duration with increased risk for obesity among preschoolers. While the physiological link between sleep duration and obesity has targeted hormonal dysregulation affecting appetite and caloric intake, little evidence exists on the factors that cause short sleep duration. Studies have rarely included children from low-income, minority backgrounds who are less likely to have consistent bedtimes or follow a bedtime routine, and more likely to have later bedtimes. Additionally, most studies have relied on parent report of sleep duration. To date, few prospective pediatric studies on sleep duration and obesity have assessed family, child behavioral and environmental factors that may clarify sleep intervention targets beyond prescribing increased nightly sleep. The long-term goal is to understand how sleep duration is determined in Hispanic children at high risk for obesity to create and to test novel interventions that can reduce risk for obesity. The overall objective here is to determine the factors that impact sleep duration. The central hypothesis is that family chaos increases bedtime behavior problems that reduce sleep duration. This causal pathway will be modified by child behaviors and sleep environment factors. This hypothesis has been formulated, in part, by our preliminary data showing increased bedtime resistance was significantly related to family chaos, after accounting for child risk factors. A cross-sectional design will be used to achieve the objectives of this proposal. The proposed study will identify the relationship between family chaos, parenting behaviors, child sleep behavior problems with sleep duration. Additionally, the study will clarify the additional impact of child factors and home environment characteristics on child sleep behaviors. The rationale for the proposed research is that once mechanistic factors for sleep duration have been identified with Hispanic families of young children most at risk for obesity, innovative interventions for increasing sleep duration can be tested for the prevention and treatment of obesity.